The estimated incidence of bladder carcinoma in the United States in 1990 is 49,000. Of these patients, 3,000 will have a cystectomy performed, and many more cystectomies and urinary diversions will be done for disabling functional disorders of the bladder.
At the present time, these patients are provided with conduits, continent pouches or ureterosigmoidostomy. Although these intestinal urinary diversions are markedly better than bilateral ureterostomies, the long list of physical and psychological complications associated with their use has spurred investigation into a total alloplastic replacement of the lower urinary tract. Several set-backs, however, have arisen with the present design of the replacement devices. The three main problem areas that still need to be overcome are renal failure from hydronephrosis, infection from urinary statis and external connections and encrustation of the luminal surface.
Most artificial bladder replacements have relied on ureteric pressure to expand a flexible bladder. Unfortunately, when these bladders are placed intraabdominally, a fibrous capsule has developed around the prosthesis restricting the filling of the bladder. This restriction can cause a retention of urine by the kidneys and the development of hydronephrosis.
In addition, in most prosthesis, gravity has been the basis of bladder emptying. Although this has been effective on bench testing, most models have been found to have large residual volumes of urine after implementation. A fibrous capsule can also cause retention of urine because it inhibits complete collapse of the bladder. The presence of this residual urine increases the risk of encrustation and can lead to infection and stone formation. Therefore, there arises the need for an artificial bladder that overcomes hydronephrosis and reduces the risk of infection and encrustation.